Methods of operating arrangements of base transceiver stations in an area-covering network

ABSTRACT

An arrangement of an area covering, cellular radio communication network having cell regions which can be contiguously replicated without interference. A central transceiver station is coupled to a base station controller and has a plurality of decentral transceiver stations surrounding and coupled to the central transceiver station. Groups of adjacent decentral transceiver stations are grouped in respective cell areas. All of the decentral transceiver stations in each cell area are allocated the same transmission frequencies, but the frequencies of each cell area are different from the other cell areas in the cell region.

This application is a continuation of co-pending application Ser. No.09/568,733, filed May 11, 2000, which is a continuation of applicationSer. No. 09/065,687, filed Apr. 24, 1998, and now U.S. Pat. No.6,128,496, which is a continuation of application Ser. No. 08/493,793,filed Jun. 22, 1995 now U.S. Pat. No. 6,128,496, which claims priorityon two German patent applications identified in the Declaration.

The invention relates to a plurality of arrangements of base transceiverstations of an area-covering radio network and to a method of operatingsuch an arrangement.

FIELD OF THE INVENTION

The invention further comprises base transceiver stations adapted to thenew arrangements and a method of subsequently compressing an existingcontinuous radio network.

DESCRIPTION OF RELATED ART

In order to operate radio telephones, in addition to the respectivemobile stations, an area-covering network of fixed transmission stationsis necessary in order to ensure interference-free radio operation at anylocation within the area of coverage.

In order to permit a large number of mutually independent radioparticipants to use their telephones simultaneously, the region ofcoverage is divided into a plurality of individual cells, each allocatedwith its own base transceiver station. By giving adjacent zonesdifferent frequencies, it is possible to identify a particular radiotelephone with a respective base transceiver station. If the radiotelephone is set to a special frequency of the current cells, radiocommunication is oriented to precisely one fixed transmission station,from which the conversation is forwarded to a base station controller.By the possibility of allocating one and the same transmission frequencyto a plurality of zones which are relatively remote from one another, avery large number of conversations can be transmitted simultaneously,using a limited number of transmission frequencies.

If one ignores interference (caused by topographical irregularitiesetc., a radio network can be put together from a plurality of basetransceiver stations arranged in a specified structure, their mutualdistance being determined by the range afforded by the transmissionpower. On the other hand, the spatial sequence of different transmissionfrequencies is on the one hand such that adjacent, base transceiverstations are allocated different frequencies and furthermore a minimumdistance is retained in base transceiver stations using the sametransmission frequencies in order to eliminate reliably anyinterference.

From these peripheral conditions, certain structures arise which can belinked together in lines to form a continuous grid. In establishing thebasic structure of such a radio network, the following parameters needto be optimised:

On the one hand, the number of cells should be as large as possiblewithout increasing the number of base transceiver stations. With thelarge number of cells, a large number of conversations can betransmitted simultaneously. On the other hand, any conventional basetransceiver station requires a high level of investment, whichconsiderably increases the cost of the radio network. It has beenproposed in the prior art to provide at each base transceiver station,instead of one non-directional aerial, three directional aerials, eachcovering a transmission or reception angle of approximately 120°, sothat the number of cells can be tripled, but such a modus operandiinvolves heavily increased aerial and installation costs.

Furthermore, the participant capacity to be handled can be increased ifthe number of channels per cell is increased. The more channels thereare available in one cell, the more participants can telephonesimultaneously from this cell. On the other hand, however, the totalnumber of frequencies should not be increased, since the transmissionfrequencies available are limited by a number of other data transmissionsystems. In order to achieve a large number of channels per cell, thefrequencies must be capable of being repeated: at the minimum possibledistance from one another. In order to meet this requirement, accordingto the prior art a hexagonal grid is used, in which the base transceiverstations are arranged in parallel columns, the transceiver stations ofadjacent columns being staggered relative to one another by half adistance in the direction of the column. This gives the associated cellsa hexagonal shape, a large number of which are joined together likehoneycomb cells in order to form a continuous network. In manyapplications, these basic areas are further subdivided by theabove-mentioned allocation of sectors to different aerials. With thehexagonal structure, an elementary system composed of seven basetransceiver stations is put together, each station requiring a differenttransmission frequency, since each cell abuts six further cells.

Where such grid structures known from the prior art are used for thebase transceiver stations of an area-covering radio network, the twoabove-mentioned optimisation criteria, in particular the product of theradio cell area and the number of fixed stations (which arecost-intensive due to being coupled to a base station controller) andthe ratio of the number of channels per cell to the total number oftransmission frequencies, cannot be varied. Although the area per cellper area can be reduced by reducing the transmission power, which meanssimultaneously increasing the number of fixed stations, because on theother hand the minimum number of cells is specified by differenttransmission frequencies (e.g. seven structure), the number of channelsper cell can only be increased by increasing the number of frequenciesas a whole.

SUMMARY OF THE INVENTION

The problem of the invention arises from these disadvantages of knownarrangements of base transceiver stations of an area-covering radionetwork, and consists in changing the basic structure of the network insuch a manner that, without increasing the number of cost-intensive basetransceiver stations coupled to a base station controller, the number ofcells per area is increased and/or without increasing the total numberof frequencies of the network, the number of channels per cell can beincreased.

To this end, the invention provides, in a first arrangement of basetransceiver stations of an area-covering radio network which are coupledat least in part to base station controllers, that each base transceiverstation coupled to a base station controller is surrounded by aplurality of further, decentral transceiver stations which are coupledto the central transceiver station and form one or more cell areas eachhaving a different transmission frequency. The advantage of thisarrangement is that the area of coverage of a base transceiver stationcoupled to a base station controller is increased by the decentraltransceiver stations without increasing the transmission power of thecentral transceiver station coupled to a base station controller. Sincecell areas having different transmission frequencies are coupled to thedecentral transceiver station, the number of cells per unit area can beincreased without having to raise the number of fixed stations coupledto a base station controller. Since the decentral transceiver stationsare not coupled to a base station controller but to a centraltransceiver station, they can be manufactured very simply and cheaply,as will be explained more fully below. By a favourable arrangement ofthe base stations and the decentral transceiver stations, the number offrequencies required for the basic coverage (1 channel per cell) isreduced (e.g. 2×1+4×1), so that within an elementary base cell (ofapprox. 9 times' the area of a single base transceiver station) it iseven possible to use all frequencies. Thus the number of channels perunit area can be increased.

It has proved advantageous if the decentral cell area(s) as a wholecompletely surround the central cell(s). This ensures on the one hand anarrangement with an optimum coverage area, which may be approximatelyfour to ten times as large as the original or central cell area. Thusthe number of base stations coupled to a base station controller isreduced by a corresponding factor. On the other hand, the central cellarea is completely surrounded by the decentral cell areas, so that thetransmission frequencies of the central cell(s) can already be used inthe adjacent transceiver station coupled to a base station controller.

It has proved advantageous if the decentral cell areas have anapproximately annular or annular sector-shaped configuration defined byapproximately arc-shaped and/or polygonal border lines. The outer cellareas together form a ring surrounding the central cell(s), so that theinner border line of the decentral cell areas ideally has the form of anarc. On the other side, in a cell region according to the invention,adjoining the total of the central and decentral cell areas of a centraltransceiver station coupled to a base station controller is a pluralityof identical cell regions which duplicate the elementary cell region inthe form of a square or honeycomb-type grid so as to form a continuousnetwork. The external outlines of the cell areas are therefore formedfrom approximately straight lines. Within the scope of the invention,both a plurality of annular cell areas can be grouped around thedecentral cell(s) and/or due to the different frequency allocations ofindividual decentral transceiver stations, annular-sector-shaped cellareas can be created within a ring.

It is within the scope of the invention that the transmission power ofthe channel units for the area coverage of the decentral basetransceiver stations is lower than the transmission power(s) of thechannel units for the area coverage of the central cell(s). Thus thedimensions of the decentral transmission stations can be reduced. Thecurrent requirement is low and can if necessary be covered by arechargeable battery. This gives rise to low manufacturing andinvestment costs and fewer problems in the grant of permission.

A practical further development of the invention involves combining alarge number of adjacent, decentral transceiver stations into one cellarea with identical frequencies. Provided that, for example, a squaregrid is selected with identical cell regions, the decentral cell areaslhave a severely distorted shape (corners of a square) so that it ismore favourable to cover these areas by means of a plurality ofdecentral transceiver stations. In order not to increase the number ofnecessary transmission frequencies, however, it is recommended toallocate to adjacent decentral transceiver stations the same frequenciesand to join these transceiver stations together to form a common cellarea. Any running time differences can be compensated.

It is within the scope of the invention to juxtapose a large number ofcell regions each formed from a respective central and a plurality ofdecentral transceiver stations in order to form an area-covering networkwith an approximately grid-type and/or hexagonal structure. By means ofsuch square and/or honeycomb-type grid structures, the terrain can becovered without leaving gaps.

In an advantageous embodiment the transceiver stations within each ofthe juxtaposed cell regions have relative positions which approximatelycorrespond geometrically. These correspondences are ascribable to theidentical base structure of each individual cell region allocated toeach transceiver station coupled to a base transceiver stationcontroller. In practice, the relative positions will, albeit slightly,fluctuate within certain limits, on the one hand due to variations inthe terrain resulting in different ranges for the transceiver stations,and on the other hand due to the local conditions to be taken intoaccount when choosing a site for a decentral transceiver station demanda degree of flexibility in planning.

It is within the scope of the invention that the frequencies of theaerials for area coverage to transceiver stations of different cellareas corresponding to one another due to their roughly geometricallycorresponding relative positions, are identical. Since both thegeometric base structure of a cell region and the transmissionfrequencies of the individual cell areas are repeated, not only thenumber of base transceiver stations coupled to a base station controllerbut also the total number of transmission frequencies can be limited toa minimum.

It has proved advantageous that the decentral part of a cell region isdivided into a plurality of, preferably four, cell areas with differenttransmission frequencies, each cell area being allocated anapproximately constant central angle with respect to the centraltransceiver station. In order to permit direct duplication of thefrequency of an elementary cell area, at least the outer ring of thecell region needs to be divided into a plurality of roughlyannular-sector-shaped cell areas; so that when such cell areas arejuxtaposed, it never arises that two cell areas with identicaltransmission frequencies abut one another. To this end, it isrecommended in the case of a square grid to divide the outer ring intofour cell areas, each with a central angle of approximately 90°, whereasin a honeycomb-type grid structure it is practical to divide the outerring into six cell areas of different transmission frequencies, eachcell area covering a central angle of approximately 60″ with respect tothe central transceiver station coupled to a base station controller.

The invention further provides that the coupling of the decentraltransceiver stations to the respective central transceiver stationcomprises a wireless point-to-point connection. Thus the laying ofcables is superfluous and the installation of a decentral transceiverstation can be: carried out without great cost and the initial outlay isthereby substantially reduced. The term point-to-point connection isunderstood to include not only radio link connections proper, but alsoconnections in which the aerial of the central transceiver station hasonly a low directional characteristic, if any, in order to address, forexample, a plurality of aerials of decentral transceiver stations of acell area, simultaneously.

Further advantages can be (obtained if, for each point-to-pointconnection to a decentral transceiver station, the central transceiverstation has its own, directional aerial and/or an opticaltransmitter-receiver device. In this case, each decentral transceiverstation is coupled by means of its own radio link or laser relay sectionto the central transceiver station.

In addition, an embodiment is conceivable in which a common aerial forpoint-to-point connection to a plurality of decentral transceiverstations is available at the central transceiver station. This reducesthe initial investment.

Furthermore, it is possible that the common aerial for connecting aplurality of decentral transceiver stations is identical to the aerialfor the area coverage of the central cell. The combined use of the areacoverage aerial of the central cell(s) is the arrangement involving theleast extra cost.

It has proved advantageous if the frequencies of the point-to-pointconnections differ from the frequencies of the area coverage of thecentral cell(s). This prevents faults arising from interference with thesignal for the area coverage of the central cell(s).

It has proved practical if the transmission power of the point-to-pointconnections is lower than the transmission power for the area coverageof the central cell(s). If directional aerials are used, together withhigh-quality receivers on the two transceiver stations communicatingwith one another, the transmission power can be reduced in order toeliminate faults due to trapping. On the other hand, a reduction in thetransmission power in the case of transmission for example via theaerial for the area coverage of the central cell(s) can be used to makeavailable to a mobile station, due to the different reception fieldstrengths, a datum which can be referred to in selecting the signal forthe area coverage.

The invention can be developed further if the frequencies of thepoint-to-point connections lie in a radio link frequency band or in anoptical frequency band. The choice of such transmission frequencies isoffered for technical reasons.

In addition, it is possible that the frequencies of the point-to-pointconnections lie in the network operator frequency range. It is thuspossible to save on possible additional fees for extra radio linkfrequencies.

If frequencies of the network operator frequency range are used, thefrequencies o the point-to-point connections my differ from thefrequencies for the area coverage to the respective decentral cell. Thusacoustic feedback can be almost completely eliminated, ensuringfault-free operation.

However, a type of coupling is conceivable in which the frequencies ofthe point-to-point connections correspond to the frequencies for thearea coverage of the respective, decentral cell. However, in this caseit should be ensured that the directional aerial of the decentraltransceiver station for coupling to the central transceiver station isspatially distant from all the aerials of the same decentral transceiverstation providing the area coverage and/or is decoupled by further meansin order to avoid interference from acoustic feedback.

Often, it is not necessary to draw up a new radio network, but tocompress an already existing radio network in such a manner that, due tothe high number of transceiver stations, not only outdoor operation of amobile telephone, but also indoor operation is possible. Here theproblem arises of finding a suitable structure in which if possible allthe sites of existing base transceiver stations can be reused, andinvestment in additional installations at new sites will be kept as lowas possible. In order to solve this problem, the invention proposes amethod of retrospectively condensing an existing continuous radionetwork comprising base transceiver stations, which are coupled to basestation controllers, wherein each existing transceiver station issurrounded by a plurality of decentral transceiver stations which arecoupled to the central transceiver station and form one or more cellareas surrounding the decentral cell(s) in the outer space thereof, eachcell area having a different transmission frequency. Thus, without thecost associated with the installation of conventional base transceiverstations coupled to a base station controller, in the critical outerspace of each central cell, a reception field strength sufficient forindoor use can be achieved. In this manner, it is easily possible toupgrade an already existing continuous radio network by insertingdecentral transceiver stations to one of the arrangements according tothe invention described above for an area-covering radio network.

The arrangement of base transceiver stations of an area-covering radionetwork according to the invention requires special base transceiverstations both for the central and for the decentral transceiverstations. The central transceiver stations coupled to a base stationcontroller are distinguished by the fact that, in addition to thechannel units for the area coverage, further channel units are availablefor the bidirectional data transfer to at least one further basetransceiver station. According to the invention, the signals for thearea coverage of the decentral cell areas are generated or processed inthe central transceiver station, so that all the decentral transceiverstations need to do is carry out amplification of the signals, in everycase combined with a frequency conversion. Therefore, for every channelof the outer cell areas of the cell region, the respective centraltransceiver station has its own channel unit. In this case each channelunit consists preferably of a monitoring component, two transmitting andreceiving units oriented in anti-parallel, and a filter assembly.

It is within the scope of the invention that the additional channelunits are connected to additional direction aerials and/or to opticaltransmitter-receiver devices. In this embodiment, the coupling of adecentral transceiver station takes the form of a true, directionalpoint-to-point connection.

In addition it is possible that the additional channel units areconnected to the aerial(s) for the area supply. If different frequenciesare used, the signals to be transmitted to the decentral transceiverstations can also be transmitted or received via the area coverageaerial(s) if the additional channel units are connected to that aerial.

It has been found advantageous if the transmission power of thetransmitters of the additional channel units; is lower than thetransmission amplitude of the transmitter for the area coverage. Thismakes possible optimum separation due to the reduced reception fieldstrength, even if a frequency of the network operator frequency band isused to couple the decentral transceiver stations, so that the mobilestation can distinguish the signal for the area coverage clearly fromthe coupling signal for a decentral transceiver station.

In an advantageous further embodiment of the invention, for one or moreof the additional direction aerials and/or opticaltransmitter-receivers, a respective time function element is provided,which is started by the additional transmitter and after the elapse ofits time constant actuates the additional receiver. Due to the spatialdistance of the decentral base transceiver stations from the centraltransceiver station, a constant running time corresponding to thedistance between the central and decentral transceiver station is addedto the variable running time, dependent on the site of the mobilestation, of a signal between the decentral transceiver station and themobile station. If a monitoring signal is consequently sent from thecentral transceiver station via a decentral transceiver station to themobile station, a reply signal can reach the central transceiver stationat the earliest with a time-lag corresponding to twice the value of theconstant running time between the base transceiver stations. Thisconstant time-lag can be taken into account by a time function elementwhose time constant is approximately twice the value of the constantrunning time between the central and decentral transceiver station. If aplurality of decentral transceiver stations is coupled via a signalaerial of the central transceiver station, it is possible to use as atime constant of the time function element a minimum or average value ofthe different, but in each case constant, running times of theindividual decentral transceiver stations.

The invention is further characterised by one or more selection circuitsin order to select, as a function of the reception field strength of asignal transmitted by a plurality of the coupled base transceiverstations, the associated coupling aerial(s). If the cells of a pluralityof decentral transceiver stations are combined into one cell area withcommon frequencies, the radio signal of a mobile station will bereceived most strongly by the decentral transceiver station in whosecell the mobile station is located at that instant. Furthermore,however, a weakened signal is received by the other transceiver stationsof this cell area and is transmitted to the central transceiver station.This selects, by means of a selection switching circuit the transceiverstation of this cell area whose reception field is the strongest andthen transmits the signal directed at the mobile station solely to theselected decentral transceiver station. Thus running time differencesbetween radio signals originating from different decentral transceiverstations can be eliminated and the transmission quality therebyimproved. The same method can also be applied to the central cell area.In this case, only the monitoring channel is transmitted over allsectors of the central cell area, but the speech channels aretransmitted over only one sector, the reception field strength of theindividual sector aerials being applied as a selection criterion.

It is within the scope of the invention to couple the additional channelunits to a base station controller. The outputs/inputs of the additionalchannel units opposing the coupled decentral transceiver stationsaccording to the system are connected in parallel in order to relaytelephone conversations to conventional channel units and are connectedvia a radio link connection and/or via cable to a base stationcontroller.

In the case of a transceiver station suitable for decentral coupling, inaddition to the aerial(s) for the area coverage, a directional aerial oroptical transmitter-receiver is available for bidirectional data relayto a further base transceiver station. This makes the costly,labour-intensive laying of a coupling cable between the mutually remotebase transceiver stations superfluous. At least at the decentraltransceiver stations, an aerial with a directional characteristic shouldbe used in order to keep the transmission power for the couplingconnection as low as possible in order to avoid interference.

It has been found advantageous that the two aerials (groups of aerials)are coupled together via two frequency-selective amplifiers connected inantiparallel. According to the bidirectional data transfer,amplification of the radio signals in both directions is necessary. Thetwo signal directions are usually distinguished by the use of differentfrequencies, which is effected by frequency-selective band filtersconnected upstream of the amplifiers.

According to the invention, a respective frequency converter is insertedbetween the frequency filter assembly and the amplifier connecteddownstream. This embodiment makes possible the use of differentfrequencies for the area coverage of the respective decentral cells aswell as for coupling to the central transceiver station, wherebyacoustic feedback and consequent faults are highly reliably eliminated.

A transceiver station according to the invention for decentral couplingfurther has a superordinate assembly for configuration, initialisationand monitoring. This assembly should above all simplify the service andtherefore has no influence on the radio signal to be relayed, apart froma purely monitoring function during operation. This signal is solelyamplified, and if necessary its frequency is converted, by a decentraltransceiver station, but otherwise is transmitted in an unchanged form.

Highly advantageously, in order to supply power to a base transceiverstation of this type, for decentral coupling solar cells can be used.Due to the low transmission power and the minimum configuration of theelectronic assemblies, the power take-up of a base transceiver stationof this type for decentral coupling is several times smaller than thepower take-up of conventional base transceiver stations. If solar cellsare used, a transceiver station of this type is fully independent, sothat after installation at the site concerned, no connection to anyservice lines is necessary. The installation of such a decentraltransceiver station is therefore extremely labour-saving.

It has been found advantageous if all assemblies, with the exception ofthe aerial or possible solar cells, are housed in a housing, which actsas a pedestal for the aerial(s) for the area coverage and/or for thedirectional aerial. This pedestal has preferably a very flat form with abase area of e.g. 1 square meter and a height of approximately 20 cm.Due to the low number of necessary assemblies, particularly in theregion of the housing edge, sufficient space still remains for receivingballast elements to increase the stability of the aerial(s).

In an advantageous further embodiment, the aerial(s) for the areacoverage are connected detachably via a plug-in mechanism to the housingacting as a pedestal. In this case, after installation of thepedestal-type housing at a favourable site, e.g. on the roof of a blockof flats, the are a coverage aerial can be inserted into the pedestal sothat mechanical assembly is limited to only a few manual operations.Then, all that remains each time is to connect the aerial to anelectricity supply.

Finally, according to the teaching of the invention, the directionalaerial is disposed on its own fixing device and is connected via aconnecting cable to the housing. In order to avoid acoustic feedback,the directional aerial is installed at a site a few meters away and tothis end requires its own fixing device. After this aerial has beenconnected to the electronic equipment, all that remains to be done areadjustments.

In the arrangement described above, it may prove disadvantageous if thebase transceiver stations coupled to the base station controller havetheir own cell which is surrounded by further cell areas. This meansthat, in addition to the frequencies required for the outer cell areas,further, different frequencies are required for the central cells, sothat although the above arrangement is an improvement over the priorart, on the whole it is not the best solution. It is therefore aparticular concern of the invention, on the basis of the above-mentionedarrangement, to permit a more extensive reduction in the number offrequencies required without restricting the advantages achieved withthe first arrangement.

To this end, the invention proposes, in an arrangement of basetransceiver stations of a continuous radio network whose area is dividedinto a large number of cell areas each with uniform transmissionfrequencies, wherein mutually adjacent cell areas are operated atdifferent transmission frequencies, that at least the cell areas whichare operated at a specified transmission frequency range are formed of aplurality of cells whose areas are covered by a respective basetransceiver station, each base transceiver station being allocated toonly one cell area.

The invention therefore dispenses completely with dividing an elementaryradio region into a central and a peripheral area. The individual cellareas can therefor—e.g. as in a honeycomb with hexagonal cells—be joinedtogether directly without the interposition of additional “central” cellareas which would have to have different frequencies from all thesurrounding cell areas. It has turned out that ideally an arrangementcan be achieved in which only every three cell areas need differentfrequencies, which are repeated periodically in the remaining cellareas, but not those directly adjacent thereto.

By dividing the individual cell areas into a plurality of cells whichare covered by a respective base transceiver station, the transmissionpower of the individual transceiver stations can be further reduced, sothat the range of the signals transmitted in a cell area issignificantly smaller than in conventional arrangements, in which only asingle radio station was provided in such a cell area. Therefore, thecommon frequency distance, i.e. the ratio of the reception fieldstrength of a signal transmitted in one cell area to the reception fieldstrength of the signal radiated at the same frequencies from the aerialsof the closest cell area, is significantly reduced and fault-freeoperation is possible. In cell areas with only one central transmissionaerial, on the other hand, the interference is so great that its usehitherto has only been practical if the frequencies were repeated, noteven in the next-but-one cell area, but at greater distances, so that alarge number of different transmission frequencies were necessary. Thuselementary cell regions used in practice have at least seven, butusually significantly more cell areas with different respectivetransmission frequencies.

Finally, it is important that each base transceiver station is allocatedonly one cell area. This makes it possible to install the individualtransceiver stations at the optimum site for one cell area, so that thesearch for a site is generally unproblematic. In particularlyunfavourable cases, where it is not possible to install the transceiverstation at a desired site, by way of compensation one or more extratransceiver stations can be inserted in order to fill up any gaps in theradio network. It is also possible at points with a particularly highlevel of traffic to install extra transceiver stations in order thus toobtain a better distance between common channels. In the prior art, thiswas only possible at great cost with only one transceiver station percell area, since an extra transceiver station with its own transmissionfrequencies was required, which necessitated a complete change in thegeometry of the network. In the present arrangement, however, neitherthe transmission frequencies of the cell areas nor the neighbourhoodlists are changed.

In a preferred embodiment of the invention, in which the cell areas havean approximately hexagonal shape and join together in lines to form acontinuous radio network with an approximately honeycomb-shapedstructure, optimum use of the transmission frequencies can be achievedif these are divided into three bands in all, each cell area beingallocated transmission frequencies from only one of these transmissionfrequency bands. Since the frequencies available only have to be dividedinto three bands, on the whole a very high number of frequencies isproduced within a cell area, so that a relatively large number ofchannels can be used per-cell area. Unlike the prior art, where in anelementary region comprising twenty cell areas with differenttransmission frequencies, for example, only approximately 5% maximum ofthe total transmission frequencies available can be used, (according tothe invention an increase in efficiency of 33% can be achieved.

An almost equally high level of efficiency can be achieved in a radionetwork according to the invention if the cell areas have anapproximately rectangular shape and are joined together without gapsinto an approximately chessboard-type radio network, because in thiscase the available transmission frequencies only have to be divided intofour bands in all, with transmission frequencies from only one of thesetransmission frequency bands being allocated to each cell area. Thus 25%efficiency can still be achieved.

Further advantages can be achieved if the base transceiver stationslocated at the periphery of a cell area have a smaller mutual distancethan base transceiver stations located in the centre of the cell area.Base transceiver stations whose cell is completely surrounded by cellswith the same frequency range and consequently lie in the interior of acell area have their transmission signal amplified by the transmissionof adjacent stations, so that their range is increased without the needfor greater transmission power. Since this amplifying effect is notavailable in the peripheral cells, because there cells border otherchannels at least in part, either the transmission power must beincreased, or if this is not possible, the distance from the transceiverstations of the adjacent cell area must be reduced in order that thereception field strength does not fall below a minimum value in theborder region between the two cell areas.

The invention further proposes that the base transceiver stationslocated at the edge of a cell area have a lower transmission power thanbase transceiver stations located in the interior of the cell area. Thepurpose of this measure is to minimise common channel interferencebetween the closest cell areas having the same frequencies by operatingthe transceiver stations which are closest to one another at theperipheries at a reduced transmission power. Although the closesttransceiver stations of two adjacent cell areas therefore have to bemoved closer together, this has no adverse effects, since the cell areasare operated at different frequencies.

The invention can be particularly advantageously improved if a pluralityof base transceiver stations are coupled via an allocated centralstation to a base station controller. This makes it possible to reducethe hardware costs in coupling the individual transceiver stations, sothat their number can be increased in an economically practical manner.

By not giving the central stations effecting coupling to the basestation controller their own cells, it is possible to install thesecentral stations on sites selected solely by the criterion for afavourable connection of the associated base transceiver stations. Thisavoids the potential problem in the main application of having to selectthe sites for the central radio station for their favourable connectionto the decentral transceiver stations on the one hand, and for anoptimum area coverage of the inner cell on the other hand. The remainingsingle criterion can usually be met with out much difficulty. If all theconditions are simultaneously favourably met, a base station and acentral transceiver station can be installed on the same site,permitting coupling via cable.

Further advantages can be achieved if each central station is allocatedall the base transceiver stations of one or more cell areas. This makesit possible to make available for all base transceiver stations of acell area common channel units for coupling to the base stationcontroller, which are disposed within the associated central station.These channel units must consequently only be available once for eachcell area, in particular in the associated central station. This permitsa reductio in hardware costs.

It has furthermore proved advantageous if in the central stations atleast one respective running time element is provided, which is startedby the transmitter of a channel unit and after the elapse of its timeconstant actuates the receiver of the respective channel unit.

It is also advantageous that each central station is coupled via apoint-to-point connection or an area-to-point connection to theassociated base transceiver stations. These may be bidirectional radioconnections, radio link connections with an omnidirectional and adirectional aerial, or optical connections by means of laser beams orthe like.

The invention can be further simplified if for all base transceiverstations of a cell area one common aerial is available at the centralstation. This may be an omnidirectional aerial for the cell area with inwhich the respective central station is installed, whilst the aerial forconnecting more remote cell areas can have a directional characteristic,albeit covering a corresponding angle of transmission in order torespond to all transceiver stations within this cell area.

It is within the scope of the invention that the frequencies used in theconnection of the base transceiver stations to the associated centralstation correspond to the frequencies for the area coverage of the cellarea concerned. In such a case, one base transceiver station inparticular provides amplification of the signal, so that in a basetransceiver station of this type the connecting aerial and the aerialfor area coverage can be coupled together direct via amplifiersconnected in antiparallel.

If on the other hand the connection frequencies of the base transceiverstations differ from the frequencies for area coverage of the cell areasconcerned, and therefore the connection frequencies lie respectively ina radio link band, then the base transceiver stations must have inaddition to the amplifiers connected in antiparallel between theconnecting aerial and the area coverage aerial frequency convertersconnected upstream of the amplifiers.

For both embodiments, a further development of the invention is suitablein which, in one or both transmitting and receiving branches connectedin antiparallel a time-lag device with an adjustable time constant isconnected. In particular in cell areas more remote from the associatedcentral station effecting coupling to a base station controller, theproblem arises that the different transceiver stations of this cell areamay have different distances from the associated connection station.Thus running time differences can arise, which within the cell areawould lead to asynchronous transmission so that, for example, thedesired amplifying effect is not achieved. This adverse consequence iscounteracted by the invention in that, in the transceiver stations sitedcloser to the connecting aerial, a greater time-lag is set than in themore remote transceiver stations. Thus a signal is still transmittedsimultaneously from all transceiver stations of this cell area.

In order to eliminate the running time problems just discussed, theinvention proposes that the time constant of a time function element inthe central station corresponds to the sum of twice the running timebetween the central station and the most remote base transceiverstation, twice the signal running time through a base transceiverstation with the time-lag set at the minimum, and a fixed, predeterminedreaction time. Since in the arrangement according to the invention thedistances between a cell area and the connection station allocatedthereto may sometimes be relatively great, the increased running timeover this distance must be allowed for by not actuating the receiver ofa channel unit until a significantly larger time constant has elapsedthan in known arrangements where the channel unit is located right inthe base transceiver station. The time constant according to theinvention must also take into account the running time corresponding tothe distance between the connecting and the base transceiver station, aswell as the signal running time within the base transceiver station.

Furthermore, the individual base transceiver stations of a cell areamust be synchronised by setting the time-lag of each of the two time-lagdevices of a base transceiver station to the differential in the runningtime between the central station and the most remote base transceiverstation of the same cell area on the one hand, minus the running timebetween the central station and the respective base transceiver stationon the other hand. By dividing the time-lag up evenly between twotime-lag devices, one of which is connected in the transmitting branchand the other in the receiving branch, it is achieved that both thearea-covering signal directed to a mobile station is transmitted fromall base transceiver stations of the same cell area simultaneously, sothat the advantageous superposition effect is achieved. On the otherhand, the directional radio signal to the connection station istransmitted from all participating base transceiver stationssimultaneously, so that a signal accumulation is achieved and arelatively high signal-to-noise ratio at least can be achieved.

Abase transceiver station suitable for the radio network conceptaccording to the invention and which is provided with a connectingaerial as well as an aerial for the area coverage—in which case theaerials are coupled together via transmitting and receiving branchesconsisting of a respective amplifier and if necessary a frequencyconverter connected in antiparallel between the aerial filters—ischaracterised in that a time-lag device with an adjustable time constantis connected in the transmitting and/or receiving branch. Thus auniversally applicable transceiver station is achieved, in which thetime-lag corresponding to the different distances from the connectingstation can be individually set.

In order that both the area-covering radio signals transmitted from thebase transceiver stations of a cell area and the connecting radiosignals can be synchronised, the invention further proposes that twotime-lag devices with an adjustable time constant are provided, one ofwhich is connected in the transmitting and one in the receiving circuit.By means of these two time-lag devices, the different signal runningtime in a respective relay direction is compensated.

It is within the scope of the invention that the two time-lag devicesare connected to the inputs and/or outputs of the transmitting andreceiving branches coupled to the connecting aerial.

Particularly for the close vicinity of a connecting station, i.e. thecell area in which the connecting station is installed, running timecompensation may be dispensable since in this case the running timedifferences may be smaller. In this case, the time constant of the timefunction element in the connecting station can also be relatively small.

Independently of the presence of one of more time-lag devices in thetransmitting and receiving branch of a base transceiver station, it hasproved advantageous if in the receiving branch a device for detectingthe field strength of the signal received is provided, which closes aswitch incorporated in the transmitting branch if a threshold value isexceeded. This measure makes it possible to actuate in a predeterminedmanner only the transceiver stations of a cell area in whose cell amobile station is in fact located, since only here is a radio contactrequired. By disconnecting the remaining transceiver stations, theoverall transmission power being transmitted is reduced, so that commonchannel interference with the closest cell area sharing the samefrequency is significantly reduced.

In this case it is practical if the threshold value is at or slightlybelow the reception field strength corresponding to the signal of amobile station located at the periphery of the cell concerned. Thus thefield strength detector according to the invention can reliablydetermine whether the mobile station concerned is located inside itscell, thus ensuring a continuous radio transmission. If a mobile stationis located at the border between two cells, it is recognised by bothdetectors of these adjacent cells and both transceiver stations areactuated. Thus the above-mentioned amplification effect is produced inthis border region, so that even in the case of such mobile tracking,advantageous signal amplification is maintained.

It has been found advantageous if the switch is opened by the receptionfield strength detector when the signal is below a further thresholdvalue. If this second threshold value is below the first thresholdvalue, a hysteresis is obtained which ensures stable operation even atthe periphery of a cell.

BRIEF DESCRIPTION OF THE DRAWING

Further features, details and advantages on the basis of the inventionwill appear from the following description of a few embodiments of theinvention and from the drawing, in which:

FIG. 1 shows a cell having an approximately hexagonal basic shape,

FIG. 2 another embodiment of a cell according to the invention having anapproximately square basic shape, supplemented along two of its borderlines by identical cells to form an area-covering network,

FIG. 3 the radio network as in FIG. 2 on a different scale, in which forthe sake of clarity the decentral cells are not shown,

FIG. 4 a block diagram of a central and of a decentral radio station,

FIG. 5 a detail of the block diagram of a further embodiment of acentral transceiver station,

FIG. 6 a perspective diagram of a decentral transceiver station,

FIG. 7 a detail of a radio network according to a further embodiment ofthe invention,

FIG. 8 a detail of a radio network of another embodiment of theinvention,

FIG. 9 a cell at the periphery of a cell area,

FIG. 10a the signals transmitted from the connection station of a cellarea plotted along the time axis,

FIG. 10b a diagram of the reply signals received by the same connectionstation, corresponding to the diagram, of FIG. 10a,

FIG. 11 a block diagram of a base transceiver station for an arrangementaccording to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows an elementary cell 1, a large number of which can be joinedtogether in lines to form an area-covering radio network having anapproximately honeycomb structure. In the centre of the cell 1 is a basetransceiver station 2, which is coupled via cable or radio link to abase station controller (not shown). By means of two directional aerialshaving a range 3, the central transceiver station 2 serves the innercells 4 a and 4 b. Within the cells 4 a or 4 b, a mobile station (notshown) communicates direct with the central transceiver station 2.

In the case shown in FIG. 1, the central transceiver station 2 issurrounded by decentral transceiver stations 5, each having an identicalrange 6. In the arrangement shown in FIG. 1, the ranges 6 of thedecentral radio stations 5 are approximately half as large as the rangeof the central radio station 2, which is achieved by suitable setting ofthe levels of transmission power. Thus the ideally circular cells 7 ofthe decentral transceiver station 5 are approximately half the radius ofthe central cell 4 a, 4 b. The decentral transceiver stations 5 are soarranged that their cells 7 complement one another to form two ringsconcentrically surrounding the central cell 4 a, 4 b.

In the decentral cells 7, communication with a mobile station viadifferent transmission frequencies from the inner zones 4 a, 4 b takesplace. However, according to a preferred embodiment of the invention,not every decentral cell 7 has its own transmission frequency. Rather, aplurality of adjacent transceiver stations 5 can be grouped into cellareas 8, whose border lines 9 in FIG. 1 are indicated by broken lines.The decentral transceiver stations 5 of the cells 7 allocated to thesame cell area 8 communicate with the mobile station at identicaltransmission frequencies. The cell region 1 shown in FIG. 1 accordinglyhas two central and six decentral cell areas 4 a, 4 b, 8, in whichdifferent transmission frequencies are used in pairs. However, anynumber of cell regions 1 can be linked together in rows to form ahoneycomb-shaped radio network, in which the division of individual Cellregions 1 into cell areas 8 and the frequency allocations in theindividual cell areas 8 can be fully identical.

FIG. 2 shows a cell region 1.0 with a different basic structure. Herealso, a central transceiver station 2 is surrounded by decentraltransceiver stations 5 in an approximate ring, but instead of ahexagonal basic shape, the cell region 10 has an approximately squarebasic shape. To form an area-covering radio network 11, a plurality ofsquare cell regions 10 are joined together in rows to form a rectangulargrid network. As can be seen from FIG. 2, in this case the cells 7 ofthe individual decentral transceiver stations 5 join up to form ahomogeneously closed radio network 11.

FIG. 3 shows a larger detail of the radio network 1.1 in which theindividual cells 7 are no longer indicated, but only the cell areas12-17, within which constant transmission frequencies are used. As isknown, none of these cell areas 12-17 borders another cell area 12-17having an identical frequency. In this embodiment, the cell area of thecentral transceiver stations 2 is divided into two cells 12, 13 havingdifferent transmission frequencies by means of two directional 180″aerials, in order to achieve a longer range 3 of the central cell area4. Thus six different cell areas 12-17 arranged in pairs havingdifferent transmission frequencies are achieved.

As can be seen from FIG. 2, the area of the cells 4 a, 4 b of thecost-intensive transceiver stations 2 coupled to a base stationcontroller corresponds roughly to a ninth of the total area.Consequently, the number of these cost-intensive transceiver stationscan be reduced to approximately a ninth, which brings the extra cost ofthe very simple, decentral transceiver stations below the break-evenpoint. Furthermore, the total number of cell areas arranged in pairs oftwo different frequencies with six in all is significantly smaller thanin conventional grid structures, where the hexagonal cell regions of onetransceiver station is divided into three sectors by the use ofdirectional 120°-aerials, so that in all twelve (four-structure with 3sectors each) to twenty-one (seven-structure with 3 sectors each) cellareas arranged in pairs with two different transmission frequencies areformed.

FIG. 4 shows a block diagram for a central transceiver station 2 and asan exceptional case only one decentral transceiver station 5. At theupper left-hand corner of FIG. 4, a base station controller 18 is shownwhich is connected for example to a mobile exchange.

The base station controller 18 communicates via a radio link connection20 to the central transceiver station 2. In this transceiver station 2is an interface component 21, which splits the signal received from theradio link aerial 22 into individual transmission channels 23 to 26.

To each transmission channel 23-26, a respective channel unit 27 to 30is connected.

Each channel unit 27-30 comprises a terminal assembly 31, whichseparates the channel 23-26 concerned according to the direction oftransmission and accordingly has two terminals 32, 33 on the down-linkside. The terminal 32, which makes available the signals arriving fromthe base station controller 18 is connected to an encoder 34, whoseoutput signal 35 is fed via an amplifier 30 to a band filter assembly37, whence the signal leaves the channel unit 27 and is passed to acombiner 38 in order to be combined with the output signals of otherchannel units 28 and transmitted to an aerial 39 for area coverage ofthe central cell area.

Via an air interface 40, this transmission signal passes to the aerial41 of a mobile station 42, for example in the form of a mobiletelephone. The reply signal of the mobile station 42 is transmitted inthe reverse direction via the air interface 40 to the receiving device39 of the central transceiver station 2, where it is allocated to therespective channel unit 27, 28 via the combiner 38.

In the band filter assembly 37, the reception signal 43, which has adifferent frequency from the transmission signal 35, is separatedtherefrom and sent to the input of an amplifier 44. This is connected onthe output side to a decoder 45, in which the signal received isprocessed and sent via the terminal 33 to the terminal assembly 31 ofthe respective transmission channel 23, 24. Via the interface component21, the radio link connection 20, the base station controller 18 and themobile exchange 19, the reply signal is fed into the conventionaltelephone network. Apart from the division into smaller sectors, thecentral cell area 4 a, 4 b is served in much the same way asconventional transmission devices.

In contrast to these, in the central transceiver station 2 according tothe invention, further channel units 29, 30 are provided, which areconnected to corresponding relay channels 25, 26 of the interfacecomponent 21. These channel units are no different in their basicequipment from conventional channel units 27, 28, but have differenttransmitting and receiving frequencies. They are coupled on the outputside to a transmitter-receiver 47 via a combiner 46.

In contrast to the transmitter-receiver 39 for the central cell 4, inthis case however an aerial 47 with a strongly directional character isused, so that the air interface 48 takes the form of a true radio linkconnection, in which case the transmitter-receiver 49 of the decentraltransceiver station 5 on the up-link side has a corresponding,directional aerial.

The aerial 49 is connected to a band filter assembly 50, which by meansof the different frequencies distinguishes the signal 51 arriving fromthe central transceiver station 2 from the signal 52 directed towardsthe central transceiver station 2. The transmission signal 51 is fed toa frequency converter 53, whose output frequency 54 corresponds to thetransmission frequency of the respective cell area 8. The transmissionsignal having the frequency 54 is then amplified in an amplifier 55 to atransmission power which ensures the necessary range 6, and istransmitted via a band filter component 56 on the output side and atransmitter-receiver 57 connected in series. Via the air interface 58,this transmission signal passes to the aerial 59 of a mobile station 60which is located within the cell 7 of this decentral transceiver station5.

The reply signal of this mobile station 60 is picked up by the receiverdevice 57 and separated from the amplified transmission signal 54 by theband filter assembly 56. Then it is transformed by a further frequencyconverter 61 into a frequency range 62 which is used for the radio linkconnection 48. After amplification by the amplifier 63, this signal 52is sent via the input-side band filter 50 to the radio link aerial 49.The signal 48 transmitted therefrom is received by the complementaryradio link aerial 47 of the central transceiver station 2 and isallocated from there in the combiner 46 to the corresponding channelunit 29, where apart from other transmission frequencies it is processedjust like the signal 40 received from the aerial 39 in the inner cell 4.The reply signal passes via the interface component 21, the radio linkconnection 20 and the base station controller 18 into the telephonenetwork.

In addition to this standard variant, in the channel units 29, 30communicating with a decentral transceiver station 5 a time functionelement can be incorporated, which is started by the decoder 34 andafter expiry of the time interval set actuates the encoder 45 in orderto compensate the constant running times on the radio link section 48.

If a plurality of decentral cells 7 are grouped into one cell area 8,all the transceiver stations 5 thus grouped can be addressed via acommon aerial 47 of the central transceiver station 2. In addition,however, it is possible to provide for each of the decentral transceiverstations; 5 its own directional aerial 47, 64 (cf. FIG. 5). In order totransmit a plurality of channels 25, 26, each of these directionalaerials 47, 64 must have its own combiner or coupler 46, 65 connectedupstream.

In order to avoid interference, selection switching circuits (not shownin FIG. 5) are integrated into the extra channel units 29, 30, whichselection switching circuits compare the signal amplitudes ascribable todifferent reception field strengths on the down-link-side inputs 66, 67,which are allocated to different radio link aerials 47, 64 and thus todifferent transceiver stations 5, and in down-link transmission selectonly the transmission aerial 47, 64 in which the highest reception fieldstrength was registered. Thus although a plurality of cells 7 arecombined into a common cell area 8, only that transceiver station 5 isever actuated in whose cell 7 the mobile station 60 is located at thatmoment. Thus the heterodyning of several signals of the same frequencyon the air interface 58 is avoided.

A constructive configuration of a decentral transceiver station 5 isshown in FIG. 6. A flat housing 68 with a base area of approximately 1square meter and height of approximately 20 cm has approximatelycentrally on its upper face 69 a plug-in device 70 for a transmissionmast 71, on which two transmitting and receiving aerials 57 are located,each having a directional characteristic of 180″. This aerials 57 areoriented in opposite directions, so that together they cover a cell 7with an approximately circular circumference. In order to reduceinterference, the aerials 57 can be inclined at a slight angle so as toconverge at the bottom. The connection of the aerials 57 to the housing68 is effected by means of cables (not shown).

A directional transmitting and receiving aerial 49 for the air interface48 to a central transmission station 2 is mounted on a post erected at adistance and is connected to the housing 68 via a cable 73. Due to thelow transmission power of the aerials 49, 57 and the minimalconfiguration of the electronics components within the transmissionstation 5, the current supply can be ensured by means of solar cellsdisposed on the upper face 69 of the housing 68.

FIG. 7 shows a detail of a radio network 101. It shows a large number ofcell areas 102, which join one another continuously so that anindividual cell area assumes the approximately hexagonal shape of anindividual honeycomb cell 103. Each cell area 102 can be circumscribedby a circle of radius 140.

Mutually abutting cell areas 102 have #different frequencies. Thus forexample the cell area 102 characterised by A can be operated in a firsttransmission frequency range, the cell areas 102 referenced B areoperated in a second transmission frequency range, and the cell areas102 referenced C are operated at a third transmission frequency range.As can be seen, accordingly three transmission frequency ranges A, B andC are sufficient to create a radio network 101 with continuouslyabutting cell areas 102, in which adjacent cell areas 102 are allocateddifferent transmission frequency ranges A, B or C.

In the embodiment shown in FIG. 7, each cell area 102 is divided intoseven cells 104 in all, although this is not obligatory. The cells 104have to be arranged within a cell area 102 not according to apredetermined geometric grid, but are arranged in a row in such a mannerthat continuous coverage of the entire cell area 102 is ensured. It isalso possible to create relatively large cell areas 102 in which acentral cell 104 is surrounded not by a single ring of approximately sixperipheral cells 104, but for example of two such rings, so that on thewhole approximately nineteen cells 104 per cell area 102 are formed.

Due to the grouping together of a plurality of cells 104 into cell areas102 having uniform transmission frequencies A; B; C; the mutualinterference even in the case of transceiver stations 105 lying indifferent cell areas but operating at the same transmission frequency,e.g. B, and having the minimum distance 107, is so slight thatinterference-free operation of the radio network is ensured. This isbecause the spacing of such transceiver stations 105 which areparticularly sensitive to common channel operation corresponds at leastapproximately to the radius 140 of a cell area 102, whilst the radius106 of a cell 104 on the contrary can be reduced to almost any size byincreasing the number of transceiver stations 105 per cell area 102.

All the transceiver stations 105 of a cell area 1O2 are coupled via acommon connecting station 108 to a base station controller not shown. Inorder to reduce the cost of hardware, a plurality of cell areas 102 areassociated with the same connecting station 108. Although preferably anapproximately hexagonal structure 109 of the cell areas 102 respectivelycoupled to a common station 108 is again preferred, this is notobligatory. Furthermore, the potential sites 110 for the connectingstations 108 can be varied within the shaded area, for example, withoutchanging the hexagonal structure 109.

In the detail from a radio network 111 shown in FIG. 8, the cell areas112 have an approximately rectangular structure 113. It is not importanthow the cells 114 are arranged within these cell areas 112; but again, ahexagonal structure similar to the one in FIG. 7 is an option. In thiscase also the transceiver stations 115 are located respectively in thecentre of a cell 114; the range 116 corresponds to the radius of thesecells 114. The minimum distance 117 between two transceiver stations 115composed of different cell areas but with the same transmissionfrequency range is slightly larger than one edge of the rectangle 113.However, this distance 117 is entirely adequate to ensureinterference-free radio operation due to the small ranges 11.6. In thiscase also, a plurality of cell areas 112 are coupled via a commonconnecting station 118 to a base station controller not shown.

In this case, for example, four cell areas 112 can be allocated to oneconnecting station 108, so that their field of influence in each casehas an approximately rectangular shape 119. The site 120 of theconnecting station 118 can be moved to virtually anywhere within thearea of this rectangle 119 or even beyond that area if coupling iseffected via an aerial with a strongly directional characteristic,although obviously the region in the centre of the rectangle 119 ispreferred, because from there the minimum running time of the connectingsignal to all transceiver stations 115 is achieved.

FIG. 9 shows a detail of a cell 104 on an enlarged scale, which islocated on the hexagonal edge 103 of its cell area 102. Within its cellarea 102, the adjacent transceiver stations 105 transmit the same radiosignal, so that in the peripheral region 121 between two such adjacenttransceiver stations 5 a signal accumulation and therefore effectiveenlargement of the range 106 by approximately 15% for example to aradius 141 is obtained.

Since the distance 123 between two adjacent transceiver stations 105composed of different cell areas 102, 102′ must be smaller than twicethe normal radius 106 of a cell 104, but the distance 122 betweenadjacent transceiver stations 105 within the same cell area 102 must besmaller than twice the radius 141 of a cell 104 enlarged by the signalaccumulation, the distance 122 between two transceiver stations 1.05 ofthe same cell area 102 can be larger than the distance 123 to atransceiver station 105 in the adjacent cell area 102′, which isoperated at a different transmission frequency range.

In FIGS. 10a, 10 b the transceiver station 124 transmitted from aconnecting station 108, 118 is plotted on the time axis 125, as is thesignal 126 received from the same connecting station 108, 118. It can beseen from FIG. 10a that the signals transmitted are divided according todifferent communication channels into individual time blocks 127 a, 127b etc. The corresponding reply signals of the base transceiver stations105, 115 being addressed are divided according to the same channeldivision into the time blocks 128 a, 128 b etc.

At the end of a transmitted signal block 127 a, in the respectiveconnecting station 118 a time function element with the time constant129 is started and after expiry of this time constant 129 the receivingdevice of the respective channel unit is actuated in order to receivethe reply signal 128 a of this channel. The time constant 129 compriseson the one hand the time 130, which corresponds to the waiting time setin conventional transceiver stations and takes into account particularlythe reaction time of a mobile station, and on the other hand an extratime interval 131, which takes into account in particular twice thesignal running time between the respective connection station 108, 118and the base transceiver station 105, 115 furthest therefrom but coupledthereto.

This ensures that the most remote base transceiver station 105, 115 hassufficient time 129 to receive the signal block 127 a, to relay it, toreceive the reply signal from the mobile station and to send the replysignal back as a signal block 128 a to the connecting station 108, 1113.

FIG. 11 shows a block diagram of a base transceiver station 105. Thisshows the aerial 132 for area coverage of the associated cell 104, viawhich communication with a mobile station 133 located in this cell 104takes place. On the other side an additional aerial 134 is providedwhich has a characteristic oriented towards the connecting station 108.Since the radio link connection 134 in the example shown lies in theradio link band, frequency conversion within the transceiver station isnecessary. This assembly therefore has almost the same structure as thedecentral transceiver station shown in FIG. 4 and referenced 5.

In contrast to this decentral transceiver station 5, in the present caseboth in the transmission branch 135 and in the receiving branch 136 ofthe base transceiver station 105, a respective additional time-lagdevice 137, 138 is connected. The time constants T of the time-lagdevices 137, 138 are adjustable in a range corresponding approximatelyto the additional time interval 131 of the respective connecting station108.

Since the time constants T of the time-lay devices 137, 138 of thetransceiver station 105 most remote from the connecting station 108 areset at zero, but in the closest transceiver station 105 on the otherhand are set at approximately half the time interval 131, it can beensured that the signal received by the connecting station 108 istransmitted simultaneously by all transceiver stations 105 of the samecell area 102, so that the desired signal accumulation is obtained inthe peripheral region 121. The signal transmitted as a reply by themobile station 133 can also, if received by a plurality of transceiverstations 105, be transmitted synchronously via the directional aerials134 to the connecting station 108.

What is claimed is:
 1. A method of operating an arrangement of base station transceiver stations in an area-covering radio network containing cell regions arranged continuously in rows, wherein each of the cell regions containing a plurality of cell areas, for each of the cell regions comprising the steps of: coupling a central transceiver station to a base station controller; coupling a plurality of surrounding decentral transceiver stations to the central transceiver station; and operating each of the cell areas contained in the cell region at respectively different transmission frequencies further comprised of the steps of: operating a plurality of adjacent, decentral transceiver stations to which the same transmission frequencies are allocated.
 2. The method of claim 1, wherein the step operating the decentral transceiver station, for each of the decentral transceiver stations is further comprised of the step of: operating the decentral transceiver station at a transmission power of a channel unit for area coverage lower than transmission power of a channel unit for area coverage of a central cell.
 3. The method of claim 1, wherein the step coupling the decentral transceiver stations to the central transceiver station is further comprised of the step of: coupling by a wireless point-to-point connection the surrounding decentral transceiver stations to the central transceiver station.
 4. The method of claim 1, wherein for each additional channel unit, operating the additional channel unit containing a terminal assembly with two terminals on a down-link side for separating signals according to the direction of their transmission is comprised of the steps of: operating an encoder coupled to an output terminal at the down-link side of the terminal assembly; operating a first amplifier receiving the output signal of the encoder; operating a band filter assembly with two terminals at an up-link side, receiving at one of these terminals the output signal of the first amplifier, and with one terminal for transmitting and receiving signals to/from an aerial; operating a second amplifier, which receives the signal output from the second terminal at the up-link side of the band filter assembly; and operating a decoder at an output side of the second amplifier, which is coupled to the second terminal at the down-link side of the terminal assembly.
 5. The method of claim 2, wherein the step coupling by the wireless point-to-point connection is further comprised of the step of: coupling by the wireless point-to-point connection the surrounding decentral transceiver stations to the central transceiver station at frequencies differing from the frequencies for the area coverage of a central cell.
 6. The method of claim 5, wherein the step coupling by the wireless point-to-point connection is further comprised of the step of: coupling by the wireless point-to-point connection the surrounding decentral transceiver stations to the central transceiver station at a transmission power lower than transmission power for the area coverage of the central cell.
 7. The method of claim 1, further comprising the steps of: the central transceiver station operating an aerial for area coverage; the central transceiver station operating a bidirectional data relay to a further base transceiver station further comprising at least one member of the collection comprising the steps of: the central transceiver station operating a directional aerial to the further base transceiver station for the bidirectional data relay; and the central transceiver station operating an optical transmitter-receiver device to the further base transceiver station for the bidirectional data relay.
 8. The method of claim 7, further comprising the central transceiver station operating a first frequency-selective amplifier coupling from the area coverage aerial to the directional aerial; and the central transceiver station operating a second frequency-selective amplifier coupling from the directional aerial to the area coverage aerial.
 9. The method of claim 8, wherein the step operating the area coverage aerial is further comprised of the steps of: inputting from the area coverage aerial by the first frequency-selective amplifier; and outputting to the area coverage aerial by the second frequency-selective amplifier.
 10. The method of claim 8, wherein the step of central transceiver station operating the first frequency-selective amplifier is further comprised of the steps of: band-pass filtering from the area coverage aerial; frequency converting from the band-pass filtering; and amplifying from the frequency converting to the directional aerial.
 11. The method of claim 8, wherein the step operating the directional aerial is further comprised of the steps of: outputting the directional aerial by the first frequency-selective amplifier; and inputting the directional aerial by the second frequency-selective amplifier.
 12. The method of claim 8, wherein the step of central transceiver station operating the second frequency-selective amplifier is further comprised of the steps of: band-pass filtering from the directional aerial; frequency converting from the band-pass filtering; and amplifying from the frequency converting to the area coverage aerial.
 13. The method of claim 1, wherein the central transceiver station has channel units for the area coverage and additional channel units for bidirectional data relay to at least one additional central transceiver station; wherein operating the central transceiver station is comprised of for each additional channel unit, operating the additional channel unit.
 14. The method of claim 13, wherein for at least one transceiver station, operating the transceiver station is further comprised of the step of: selecting an associated coupling aerial as a function of the reception field strength of a signal relayed by a plurality of coupled base transceiver stations.
 15. The method of claim 13, wherein for each of the channel units, the step operating the channel unit is further comprised of the steps of operating transmission devices having a transmission power.
 16. The method of claim 15, wherein the transmission power of the transmission devices of the additional channel units is lower than the transmission power of the transmission device for area coverage.
 17. The method of claim 13, wherein for at least one transceiver station, the step operating the transceiver station is further comprised of the step of: operating a time function element is further comprised of the steps of: starting by a transmitter device; and actuating a receiver device after the elapse of a time interval.
 18. The method of claim 17, wherein for at least one transceiver station, the step operating the transceiver station is further comprised of at least one member of the collection comprising the steps of: operating a directional aerial; and operating an optical transmitter-receiver. 